Analysis of the origin of domestic animals is of wide interest and has many practical applications in areas such as agriculture and evolutionary biology. Identification of an ancestor and comparison with the domesticated form allows for an analysis of genetic, physiological, morphological and behavioral effects of domestication. Because fox breeding has been an ongoing process for over a century, differences are expected between farm and wild populations at the chromosomal level. The aim of this work was to analyse polymorphisms at the chromosomal level in foxes raised on farms and those living in the wild. Blood samples and lung tissue served as the experimental material and were obtained after slaughter of 35 foxes, including 28 breeding animals and 7 wild animals. The classical cytogenetic method was used including AgNOR technique, as well as molecular methods such as fluorescence in situ hybridization (FISH), and primed in situ labeling (PRINS). Analysis of the number of B chromosomes showed the presence of polymorphisms in foxes from both studied populations, but there was no correlation between the number of B chromosomes and the origin and gender of particular animals. An analysis of active nucleolar organizers showed the presence of a large number of polymorphisms and a tendency towards reduction of the number of NORs in the captive-raised population.